Pages

Monday, August 12, 2013

Snowflake macro photography

My main hobby is taking closeup snowflake pictures. Real snow crystals are amazing objects for macro photography, thanks to their beauty, uniqueness and unlimited diversity. Even after eight winters of regular photo sessions, seeing thousands of snowflakes in all their details, i do not get tired to admire new crystals with amazing form or an incredible inner pattern.

Some people think that snowflake photography is a complex matter, and requires expensive equipment, but in fact it can be inexpensive, very interesting and quite easy, after some practice.

I capture every snowflake as short series of identical photos (usually 8-10, for most interesting and beautiful crystals - 16 shots and more), and average it (after aligning, for every resulting pixel take arithmetical mean of corresponding pixels from all shots of series) at very first stage of processing workflow. Averaging technique dramatically reduces noise and reveals thin and subtle details and color transitions, which almost unseen in every single shot from series, because they masked by noise.

My camera works with CHDK - Canon Hack Development Kit: this is resident program, which works together with firmware and expands camera functionality. Once installed on SD card, it starts automatically when camera turned on. This "alternate firmware" is really wonderful thing, which turns compact camera into powerful tool, capable of RAW writing, exposure bracketing for HDR and focus bracketing for focus-stacks, executing scripts on BASIC-like language and many more. Installing and uninstalling CHDK is easy and non-destructive process. I highly recommend CHDK to photographers with compatible cameras (it supports lots of Canon compacts).

CHDK is not necessary for snowflake macro photography, but it is very useful, because it support RAWs as well as standard JPEGs and able to execute scripts. I use script Ultra Intervalometer with zero delay between serial shots. With this setting, it works as continuous series with auto focusing before each shot. Re-focusing helps with small shifts of camera and/or snowflake, which happens very often.

Equipment and place

The necessary equipment is not expensive (i already had everything i need: a camera, lens Helios 44 and all other components, so this macro gear costs me nothing).

I think, almost every compact camera is suitable for this simple setup, especially one with good optical zoom and high resolution sensor. Instead of Helios 44, many other external lens can be used. I've successfully tested also Industar 50 and Zenitar 2/50 (both lens also was manufactured in USSR for film SLR camera Zenit). For testing macro capabilities, you can simply hold external lens in front of camera, working in maximum zoom mode, and take a few test photos. In my case Helios works fine, and i even managed to capture some nice pictures of insects and spiders, holding external lens in hand (though this was not comfortable without mounting lens in front of camera some way).

The smaller the focal length of the external lens and bigger - of built-in camera's optics, the greater magnification is achieved, but less depth of field is obtained. Compact camera, with a sensor of small physical size, have an advantage over DSLRs in the depth of field and mobility, allowing you to take pictures quickly and easily change the location and shooting angle. But small sensor have much higher noise level.

My shooting place is open balcony of my house. Less than half of it covered by roof, other part is under open sky. When the snow is light, i photograph on the open part, choosing the most beautiful and interesting snowflakes fell on the background, and clean background periodically, when it becomes covered by snow. When snowfall is heavy, usually i photograph under the roof, bringing the background under the snow for short time to collect new crystals. I'm lucky that i have such nice place, where nobody disturbs me and i can return into house when i freeze.

First efforts

Initially, two findings in the web inspired me to try snowflake photography:

First one was famous site SnowCrystals.com by Kenneth G. Libbrecht, professor of physics at the California Institute of Technology (Caltech). I could not believe my eyes when i first saw his photographs of snowflakes - so amazing and beautiful they are. For me, snowflakes by Kenneth Libbrecht, Don Komarechka, and several other excellent photographers (mentioned further), are standard of quality and an ideal to aspire.

But, as many people, who saw really good snowflake photos first time, i thought that it is impossible to capture something like this for amateur photographer, without any experience and expensive microscope. Now i know that this is completely wrong! Every photographer with simple point-and-shoot camera can take very good snowflake pictures. For this type of photography, patience, persistence and luck mean much more than any expensive photo technique. It is necessary to wait for good snowfalls, which brings a large number of interesting and beautiful snowflakes. They happens not so often (at least, in Moscow), but just one lucky day can give you lots of wonderful photographs, worth weeks and months of waiting and capturing only non-interesting specimens.

For example, my best snowflake photos from winter 2013-14 was taken in two successful days: 16 and 26 January, though i photographed during the whole winter at every opportunity:

Second discovery convinced me that. On russian photography site i stumbled across two photographs of snowflakes (sorry, can't remember author's name). These were photos on a dark woolen fabric (material that is often used to capture snowflakes, one of my favorite backgrounds: it have several important advantages). Against this background, snowflakes looks very impressive - like precious gems in a jewelry store. And this beauty was photographed by a conventional compact camera without a microscope! From that day i was waited for the winter like never before, to try snowflake photography by myself.

In the beginning, in December 2008, i started photograph snowflakes in standard macro mode of camera, without any optical extensions or any tricks. I just tried several backdrops: colored plastic folders for paper, dark green carpet, and black wool fabric. Canon Powershot A650 have 12-megapixel sensor and good macro mode, in which it can focus from 1 centimeter from the lens. That's enough to get good pictures of snowflakes, but in very low resolution: it is necessary to cut out a small central part with the object and some surrounding background from the whole frame:

Source snowflake photo, 4000 x 3000

Processed picture of snowflake, 800 x 600

Depending on the size of the snowflake (it can vary in a very wide range) size of the finished picture was from 640 x 480 to 1024 x 768 pixels, no more. This was only suitable for the web or collages, but not for prints.

Dark and bright photos

In those days i photographed snowflakes in two ways, and today i use both with some improvements:

1. For dark images with bright snowflake i use dark background (at first, it was a green rug for footwear, made of artifical fibers, later - black woolen fabric) and natural light of cloudy sky. Background laid out on a stool, and as soon as i see among the fallen snowflakes good and interesting crystals, i photograph them at an angle, touching background with both hands and the bottom of camera for steady shots (light on cloudy winter days rather dull, and shutter time is not too short). Camera shoots in macro mode from the minimum possible distance at which it can focus. In camera settings i choose to focus on a small central area instead of the standard auto focusing on multiple zones - it allows to focus precisely on the center or front edge of snowflakes; and set exposure metering mode to central spot, instead of evaluating on whole frame (otherwise small bright snowflake on a dark background will be overexposed; alternative ways is to use negative exposure compensation, or set shutter speed manually).

2. For images with bright background and transparent silhouette of snowflake - shooting on glass surface with backlight. On the floor of the balcony i put upturned legs up stool, on its legs put four pieces of foam rubber (anti-slip), and over them - a sheet of glass. To shooting aimed straight down without any camera shake, i make a simple replacement of tripod: i took small plastic bottle, and from middle part of it cut out cylinder with height of 5.5 centimeters. That height is selected in such a way that the camera lens, pushed in, did not get to the bottom 1 centimeter (this is minimum focusing distance of Canon Powershot A650 in macro mode). When snowflakes falls at the glass, i put this tube with camera over a chosen snowflakes, and shoot with 2 seconds delay (using custom timer function in camera menu), so i have time to move out hands from camera for steady shot.

With left hand, i light snowflake from below of the glass with LED flashlight. I put white plastic bag on flashlight - it serves as diffuser, making LED light more uniform. Light is strong enough to photograph even at night, with lowest ISO and short shutter speeds. If flashlight pointed straight up, we will see on camera screen only dark outlines of snowflake and its internal structure on a light background (it looks pretty boring, at my taste). If we move flashlight a little sideways, and point it to snowflake at some angle, snowflake silhouette becomes volumetric, with dark and light contours. This looks more interesting and shows internal structure of snow crystal much better. I cool sheet of glass outside at least 15 minutes before start photograph, otherwise it melts snowflakes. When the glass is covered with a layer of snow, i remove it with dry towel.

From 2013, for photos on glass i use simple multi-colored lighting: instead of white diffuser, i put on flashlight a fragment of plastic bag with some color pattern or text (for example, white / orange or blue / white / pink). Because i hold flashlight at some distance from glass with snowflake, it is completely out of focus; resulting picture will contain only smooth color gradient at background and snow crystals with multi-colored facets. Even if i do not like colors on source photos, this is not a problem: i can easily convert existing colors to more pleasant variants, applying custom contrast curves on channels A and B in LAB color space.

Averaging technique

Since 2011, i capture every snowflake as short series of identical shots. When processing, this series averaged and merged into one picture. This technique dramatically reduces noise (improve the signal / noise ratio of the image) and reveals weak and subtle details, masked in each single photo by noise. Here is article about averaging technique.

Macro setup with external optics

In 2012, i started using external optics for better magnification of snow crystals, and built simple optical add-on for my camera. This macro rig based on lens Helios 44M-5, taken from old camera Zenit:

At first, i pick narrow wooden board (around 30 centimeters long and 6 centimeters wide) and temporary attached lens Helios 44 to one end, mounted reversely: back lens to object, front lens to camera. Then, i placed camera on board next to Helios, turned it on and used optical zoom mode at maximum (6x). I aligned camera so that internal lens almost touched Helios and both lenses were on the same optical axis. Then, i mounted Helios permanently (with duct tape, using many layers), and drilled through board an opening for screw, suitable for camera's tripod socket. I attached the camera with a screw from below and additionally with small metallic bracket, glued to the side of wooden board: it holds opposite side of camera, so it didn't move when attached. Camera attaches and detaches easily and quickly. On back side of Helios (which is front side of whole macro setup) i attached three standard narrow extension rings from camera Zenit (this is necessary only when shooting vertically on glass, in other cases i detach them). These rings keeps lens Helios at needed focusing distance from snowflakes on glass (2,5-3 centimeters in my case). The point of contact of internal and external lenses i covered with sleeve, created from black plastic bag: it protects this zone from outer light, snow, ice and drops of water. Also, i glued thin rubber at front edge of board (below Helios) and on outer extension ring, which stands on glass: this is for anti-slip.

The whole construction has turned out quite firmly and steadily stands vertically on extension rings. I used it 3 winters, and it does not require any repairing. I simply put this setup on glass over the chosen snowflakes and photograph in maximum optical zoom mode. Auto-focus works fine, camera focuses through external optics without any issues.

Here is scheme of this macro setup (larger image opens on Flickr):

Assembled rig (definitely, not the most beautiful thing in the world):

All ready, needs only snow:

Snowflake photography on opaque backgrounds

This setup i also use to shoot on dark opaque background (with detached extension rings). For these photos i use natural light of cloudy sky. I shoot at angle: put rear side of board on small desktop tripod (Continent TR-F7). On top of tripod, i attached small and flat piece of wood for better stability. Bending flexible legs of tripod, i easily adjust angle, at which camera pointed at snowflake. Near side of board (with front lens) lays at background. I capture serie for one crystal, then quickly move and point macro setup to next snowflake.

My main background for these shots is black woolen fabric. It have very useful properties, thanks to thin, rigid and springy fibers, rising from the fabric and going in all directions. First: when snowflakes falls to such tissue, usually they hanging in the air, touching the fibers only at few points, and this slows down melting. Second: snowflakes often stuck and held by fibers so well that the wind can't blow them away, or even move. Third: when needed, it is easy to move or lean snowflake in desired direction with toothpick, and usually crystals held in new position by fibers and do not fall or shift. But, despite the practicality, i do not particularly like the look of this background in the photographs. When process photos, often i am trying to clean up most distracting fibers near to snowflakes.

When capturing snowflakes at an angle, immediately becomes apparent that the depth of field is too small even if we use most narrow aperture. The obvious solution is to use focus stacking technique, at least with 3-5 shots, although this is not easy to shoot large series for combined focus stacking and averaging techniques, when our object quickly melts and sublimates. Alternate solution is easier: when snowflake rests on the fibers of wool fabric, it is not difficult to lean it into the desired position. So it is sufficient to aim macro setup at crystal, and then, looking from the side, change the slope of snowflake with a toothpick so that it will lie parallel to the plane of the lens - and in this case it will fit in focus completely. Despite its apparent fragility, snowflakes surprisingly strong and usually withstand a few touches by toothpick without any visual signs of damage.

I constantly use wooden toothpicks for this photography, and always keep in the cold a few pieces in reserve. Besides of tilting snowflakes to the desired angle, i use them to raise snowflakes, too deeply seated in the wool fibers, as well as moving out crystals that fell next to the selected for shooting, and even separate snowflake clusters to single crystals.

Camera settings

I set these camera settings: shutter priority mode (TV); exposure time: 2 seconds (this is much longer shutter speed that camera would select with auto settings); focusing by single central area, instead of multiple zones; exposure metering mode to central spot, instead of evaluating on whole frame (otherwise snowflake on dark background will be overexposed). All other settings on Auto.

With these strange settings, camera tries to lower exposure (for keeping it normal at central spot with bright snowflake). Camera lowers ISO to minimum and selects most narrow aperture; but exposure still too high, and finally, camera lowers exposure time. The result is exactly what we need: photos with correct exposure, minimum noise and maximum possible depth of field. Of course, it is possible to set all the parameters in manual mode (M), including a minimum ISO and most narrow aperture, but then we have to set the shutter speed manually and adjust it when lighting conditions changed.

But not every Canon compact camera will work like this: for example, Canon G10 does not adjust the shutter speed set in TV mode, and over-exposures photos with such settings. For these cameras will likely be optimal to set all parameters in manual mode instead of TV.

For photos on glass i use the same parameters, except for starting shutter speed in 1 second (in this mode we have much more light) and exposure metering - center-weighted or evaluative: usually we have bright background with slightly darker snowflake, and exposure metering by central spot can lead to overexposed background.

Shooting strategy

In most cases, i capture snowflakes instantly when they fall on background (wool fabric or glass), without moving them anywhere, and only adjust their placement with toothpick, if it needed. This allows me to shoot fast and take lots of photos. Although the percentage of bad quality images is quite high, and often background contains many unfocused crystals and ice debris (they have to be removed at processing stage), still i can get a decent number of good shots in a limited time. This is important if good snow does not last long.

An alternative method also gives good results: keeping clean background somewhere under a canopy and move the best crystals on it one by one, using a fine watercolor brush. Transferring snowflakes with brush - a fairly simple process, it requires no special skill. We can use very large collection board under the snow, and will have much more interesting crystals to choose from. The disadvantage of this method - a rather slow shooting process.

Examples

Some unprocessed, straight out of camera JPEGs to compare: standard macro mode vs using external optics. Please click at images to open them in full 12-megapixel resolution:

Standard macro mode

With Helios 44

Also i prepared another before and after comparison table with unprocessed, straight out of camera photos and final snowflake pictures.

Here is summer photos, taken with this macro setup (portraits of house fly and common wasp, surface of strawberry with visible cell structure and pollen grains of Alcea Rosea):

Postprocessing

Shooting is fast and easy, but my processing workflow takes significant time and effort. I'm trying to get the most quality out of available sources, and make picture with low noise, but preserving all possible details. At first stage, i convert source shots from RAWs to TIFFs, then align and average series for selected crystal. Then i work with sharpening, additional noise removing, cleaning background from ice debris, unfocused crystals and other distracting elements, color toning (i prefer adding blue colors to my snowflake pictures: in most cases, source shots looks too monochrome and not appealing, at my taste) and finally, contrast curve. Also, my workflow includes manual drawing precise mask, needed for separating crystal from background. This mask used for process crystal and background with different sharpening and noise removing settings. Drawing these masks requires patience, accuracy and lots of time, especially for big and complex snow flakes.

Snowflake pictures

This is closeup snowflake images, taken with new macro setup and post-processed:

Rainbow snowflakes

This is snowflakes with clearly visible thin film interference effect (it described in Wikipedia). Same effect produces rainbow colors in soap bubbles, for example. Unlike bubbles, in snowflakes this effect can be seen only occasionally: if snowflake contains air cavities in the center, and interleaved layers of ice and air are very thin:

All these snowflakes, and many other (more than hundred) are available as prints in these print-on-demand services:

Artist website (and its mirrors at Pixels.com and FineArtAmerica.com), powered by FineArtAmerica / Pixels: one of the largest, most-respected giclee printing companies in the world with over 40 years of experience producing museum-quality prints. All prints are produced on state-of-the-art, professional-grade Epson printers:

See also

• Don Komarechka, Canadian based professional photographer, who recently published excellent book about his way of snowflake photography, physics of ice crystals formation and many other interesting topics:

Also, don't miss this ultra high resolution poster, created by Don: «The Snowflake».

• SnowCrystals.com, created by Kenneth G. Libbrecht, American professor of physics - great resource about snowflake physics and photography. I especially recommend section about snowflake classification with photo examples of each type: Guide to Snowflakes. Also, Kenneth's fantastic snowflake collection available on Flickr. I especially recommend his album Designer Snowflakes with amazing and extremely beautiful crystals, artifically grown in laboratory.

• My mother shoots snowflakes with similar technique (i've built another macro setup for her Canon G10, similar to my own). You can see her snowflake album on Flickr.